Conventional multiphase DC/DC converters may employ two or more identical, interleaved single-phase DC/DC converters placed in parallel between the input and the load. Each of the n “phases” is turned on at equally spaced intervals over the switching period, so that the effective output-ripple frequency of the multiphase system is n×f, where f is the operating frequency of each converter, and n is the number of phases in the converter. This provides better dynamic performance and less decoupling capacitance than a single-phase system. Also, the multiphase converter system can respond to load changes as quickly as if it switched at n times as fast, without the increase in switching losses. Therefore, it is able to respond to rapidly changing loads, such as modern microprocessors.
However, conventional multiphase converter systems are not economical because they require several single-phase converters with all associated elements.
For systems with a high number of phases, it is difficult to route pins of each single-phase converter over a board. Also, individual single-phase converters in the system would influence performance of the other converters, for example, the individual converters can pick up noise from the other converters.
For buck-boost multiphase systems, the control scheme for switches are so complicated that it is difficult to make all phases to perform in a coordinated way. For example, one single-phase converter can operate in a buck-boost peak mode, while the other can operate in a buck-boost valley mode.
Therefore, there is a need for a new technique that would enable a DC/DC converter to operate as a multiphase DC/DC conversion system without the disadvantages of conventional multiphase systems.